Compositions and methods for removing minerals from hair

ABSTRACT

A composition for use in removal of minerals from hair is disclosed herein which comprises the combination of an acidifying agent, a reducing agent, a chelating agent, a gelling agent and water. A synergistic combination of chelating agents is disclosed. Also disclosed herein is a process for packaging the inventive compositions, and a method for removal of mineral residues from hair by use of compositions as disclosed.

This application is a continuation of application Ser. No. 08/387608,filed, Feb. 13, 1995 now abandoned, which is a continuation of Ser. No.08/041,530 filed Apr. 1, 1993, now abandoned which is a continuation ofU.S. Ser. No. 07/807,096 filed Dec. 13, 1991 now abandoned.

BACKGROUND

The present invention relates to the field of hair treatment andparticularly to mineral removal from the hair shaft.

Despite the widespread need for a simple and effective treatment toremove minerals from the hair, prior art methods have been ineffectivein removal of these mineral deposits from the hair shaft. More than 50percent of the American people use well water which can lead to mineraldeposits on hair and scalp. Many communities have municipally supplied"hard" water which may lead to mineral deposits on hair. Mineraldeposits may discolor the hair shaft and also alter the texture of hairto make hair brittle. Minerals must also be removed prior to applicationof permanent hair treatments. Minerals in hair may also lead to unwantedhair color when hair is bleached or color is applied. Common minerals inwater that form deposits on hair include calcium, magnesium, iron andcopper, along with small amounts of lead, chromium, tin and zinc. Theseminerals are metals that carry a positive electrical charge and may befound in their higher oxidation states. These metals in their higheroxidation states may act as oxidizing agents.

Common mineral residues such as iron, copper and lead produce obviousdiscoloration of hair, in which iron is reddish orange, copper is greenand lead is black. Calcium and magnesium are not colored, but manifesttheir presence by giving the hair a dry, brittle feel. These mineralsform deposits that can not be removed from the hair and skin throughnormal processes and techniques.

Hair and skin are composed mainly of protein. The protein in hair isarranged in such a way that the tertiary protein structure carries aweak negative electrical charge which may attract minerals that have apositive charge. The protein in hair is composed in part of asulphur-containing amino acid called cysteine. Two cysteine moleculescan bond together through oxidation to form cystine, which has acovalent disulfide bond that is quite strong. The mineral deposits inthe water which contain a positive charge are attracted to the negativecharge on the hair strand and may oxidize the free cysteine by acting asoxidizing agents. These oxidizing agents may also form covalent bondswith the cysteine residue.

Heretofore, these mineral protein interactions were considered to bemostly ionic and mechanical, due to the attractions between the positivecharge on the mineral and the negative charge on the hair. This beliefled previous attempts to remove mineral build-up to focus on the use ofalkaline chelating solutions containing one or more derivatives ofethylene diamine tetraacetic acid (EDTA). These previous attempts toreduce mineral build-up on hair have only had marginal efficiency due totheir focus on the ionic component of this problem.

It is important for minerals in the hair to be removed prior to apermanent because the minerals interfere with the chemical reactions inthe permanent wave systems utilized to relax the hair shaft. Salts ofthioglycolic acid are used as reducing agents in permanent wave systems.These salts are generally ammonium, calcium or sodium derivatives ofthioglycolic acid. Thioglycolate, when applied to hair, breaks disulfidebonds, which thereby relaxes or straightens the hair and allows theprotein structure to be rearranged into a different conformation throughthe process and treatment. If thioglycolate is added to hair containingiron, iron binds to the thioglycolate ion and produces an intensereddish purple color. Typically, iron laden hair will literally drippurple solution off the hair when a permanent wave solution is applied.This effect of turning the hair purple is undeniably an undesirableeffect. Minerals that are covalently bound to the hair strands alsointerfere with the ability of the thioglycolic acid to interact with thehair strand to relax, straighten, or provide a new set for the hairthrough the process and treatment.

SUMMARY OF THE INVENTION

One aspect of the present invention relates to a composition suitablefor removing minerals from hair comprising an acidifying agent, areducing agent, at least one chelating agent and a gelling agent. Thiscomposition reduces oxidized minerals in a weakly acidic environment,thereby preparing the minerals for the chelating agent to sequester andremove the minerals from the hair strand. Another aspect of the presentinvention involves the process of packaging a weakly acidic compositionsuitable for removing minerals from hair in an air-tight package in anoxygen-free environment. This process of packaging is necessary tomaintain the effectiveness of the composition.

It is an object of the present invention to provide a weakly acidiccomposition suitable for removing minerals from hair which includes anacidifying agent, a reducing agent, at least one chelating agent and agelling agent.

It is another object of the present invention to provide a process ofpackaging a weakly acidic composition suitable for removing mineralsfrom hair which includes providing an acidifying agent, a reducingagent, at least one chelating agent and a gelling agent and packagingsaid agents in an air-tight package in an oxygen-free environment topressure the effectiveness of such agents.

A further object of the present invention is to provide a process forremoving minerals from hair shafts which may reduce hair discoloration,improve texture and also increase the effectiveness of permanents andother hair treatments.

Further objects and advantages of the present invention will becomeapparent from the description of the preferred embodiment which follows.

DESCRIPTION OF THE PREFERRED EMBODIMENT

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to the preferred embodiment andspecific language will be used to describe the same. It willnevertheless be understood that no limitation of the scope of theinvention is thereby intended, such alterations and furthermodifications in the device, and such further applications of theprinciples of the invention, being contemplated as would normally occurto one skilled in the art to which the invention relates.

Hair is comprised of hair shafts which are further comprised of proteinthat may bind minerals by both ionic bonds and covalent bonds as will bemore fully described. The present invention in various embodimentsprovides compositions and processes for removing the minerals from hairshafts.

The inventive compositions include four ingredients, an acidifyingagent, a reducing agent, a chelating agent and a gelling agent. Thecompositions are able to reduce metallic minerals and sequester theseminerals from the hair protein by use of chelating agents. The weaklyacidic environment aids in removal of the minerals by reducing the bondstrength of the minerals to the hair protein. The reducing agent alsofunctions to weaken the cysteine-metal bond strength and increase theefficiency of the chelating agents. The chelating agent removes metalsfrom the hair shaft after the acidifying agent and reducing agent haveweakened the bond that retains them. The invention is formulated as agel to retain the composition in intimate contact with the hair shaft.The inventive compositions are preferably applied in combination withheating of the compositions and/or hair, as the heat expands the hairshafts to provide entry of the composition into the hair shaft andincrease the reaction rate.

Several of the ingredients of the composition may serve more then onefunction. Ascorbic acid serves as both an acidifying agent and reducingagent. EDTA, citric acid, and gluconic acid are chelating agents thatalso serve as acidifying agents due to their weakly acidic nature.

Weak acids and their salts are utilized in the inventive composition toprovide an acidic environment that is safe for use on the hair shaftsand which weakens the bond strength of the cysteine-metal bond. Thisweakening of the bond allows the chelating agent to perform moreefficiently in removing the minerals from the hair shaft by reduction ofthe bond strengths. Although a specific pH is not critical to theoperation of this invention, it is advantageous to provide a pH in therange of 2 to 5, preferably about 2.5.

A reducing agent is included in the inventive composition to transferelectrons to the oxidized iron, copper, lead, chromium and tin and otheroxidized metals to reduce their oxidation state and thereby lower thestrength of the cysteine-metal bond. For example, the reduction of ironfrom Fe³⁺ to Fe²⁺ reduces the strength of the cysteine-iron bond therebyincreasing the ease of sequestration of the iron by the chelating agent.The reducing agent must be carefully chosen so that it has sufficientstrength to provide effective reduction of the oxidized cysteine-ironbond and is gentle to hair so that the structure of the hair shaft isnot injured. The electrode potential of the reducing agent is selectedso that it is below that of the metal ions but above the potential ofthe cysteine bond, otherwise the structure of the hair will be destroyedupon treatment. Ascorbic acid is a sufficiently strong reducing agent toallow the chelating agent to remove the unwanted minerals from the hairshaft and is also safe for use on hair. Ascorbate or ascorbic acid is apreferred reducing agent and its minimum effective strength is about 2.1percent, although a higher concentration may be used.

Once the ascorbic acid has come in contact with the cysteine metalcomplex and the metal is reduced, a strong chelating agent in aneffective concentration must be available to attach to the reduced metalions. To be effective, the bond energy between the reduced metal ion andthe chelating agent must be stronger than the mostly covalent bondbetween the metal ion and the cysteine ion or the bond energy of themetal ion cysteine bond must be further reduced. The weakly acidicnature of the inventive compositions, in combination with the reducingagent reduces the metal cysteine bond strength to the point that themixture of chelators or chelator may be used effectively. A chelatingagent mixture of disodium EDTA, sodium or potassium gluconate and citricacid with sodium or potassium citrate or various combinations thereofmay be utilized to provide a chelating matrix. A mixture of chelatingagents provides a more effective metal chelation to help remove themetals from the cysteine residues located in the tertiary proteinstructure of the hair strand. A mixture of 1.5 percent disodium EDTA,2.7 percent sodium gluconate, 0.42 percent citric acid and 0.42 percentsodium citrate (w/w) in water in these proportions provides an intensesynergistic chelating environment that maximizes chelating agent ion tocysteine-metal ion contact and is a sufficient quantity of chelatingagent to remove minerals from hair. The proportion of chelating agentsin the synergistic mixture, in dry form, is approximately 30 percentdisodium EDTA, 55 percent sodium gluconate, 8 percent citric acid and 8percent sodium citrate (w/w).

A gelling agent is included in the inventive composition to retain thecomposition in intimate contact with the hair shaft. The gelatinousconsistency of the inventive composition is necessary to retain thecomposition on the hair shaft and allows the hair stylist to force thecompositions into the hair shaft by squeezing with application of firmpressure.

Various combinations of the four ingredients may be formulated,depending on intended use. Ingredients simply need be compatible andefficacious with one another, and present in amounts suitable to performthe functions indicated. An especially preferred embodiment of theinvention includes 2.1 percent w/w ascorbic acid which is utilized as areducing agent and an acidifier, disodium EDTA 1.5 percent, sodiumgluconate 2.7 percent, citric acid 0.42 percent and sodium citrate 0.42percent w/w in water to produce a synergistic chelating environment, and1 percent w/w xanthan gum which provides a medium for holding thecomposition onto the hair shaft thereby enabling the stylist or user tosqueeze the acidic gel into the warm expanded hair shaft. The especiallypreferred embodiment of the invention in dry form is about 26 percentascorbic acid, 18 percent disodium EDTA, 33 percent sodium gluconate, 5percent citric acid and 5 percent sodium citrate and 12 percent w/wxanthan gum.

The invention may be packaged or as a dry powder to which the user addswater or as a ready to use gel for convenient application. A preferredprocess for packaging the invention includes packaging the acidifyingagent, reducing agent, chelating agent and gelling agent in an air-tightpackage in an oxygen-free environment. The oxygen-free environment maybe achieved through use of nitrogen gas in the packaging procedure. Topackage the invention as a gel, the acidifying agent, reducing agent,chelating agent and gelling agent are combined with water in anoxygen-free environment. The resulting weakly acidic gel is packed in anair-tight, oxygen-free package. The invention may be packaged undernitrogen to reduce oxidation. Actual mixing and packaging steps may beperformed in accordance with conventional methods for handling materialsin an oxygen-free environment. It is important that the invention bestored in an air-tight container since exposure to the atmosphere mayallow the reducing agent to become oxidized and thereby negate itsusefulness as such.

EXAMPLE 1 HAIR STRAND TEST

Initial tests of this invention were performed on six people. These andother tests have demonstrated that after 45 minutes iron is removed fromthe hair strands. This testing procedure may be useful at differenttiming intervals to determine the length of time needed for theinvention to remain in contact with the hair shaft to remove theminerals for initial use of the inventive process. A stylist is able togauge the correct amount of exposure time for the inventive compositionsafter a brief experience with the invention.

A powder mixture was prepared that included sufficient amounts of eachof the following components to yield 2.1 percent w/w ascorbic acid, 1percent w/w xanthan, 1.5 percent w/w disodium EDTA, 2.7 percent w/wsodium gluconate, 0.42 percent w/w sodium citrate and 0.42 percent w/wcitric acid when added to 60 g. of water. Two hair samples were takenfor iron tests; one was used as a control, and one was treated with theinventive composition. The control was tested with thioglycolate, whichis used for permanents, to demonstrate tie presence of iron. The testsample was treated with the inventive composition for 45 minutes. Thecontrol sample was utilized to determine whether any iron was present inthe hair. If iron is present, a intense reddish purple color will becomeevident. If no color develops, the hair may not be in need of treatment.

In order to prepare the test sample, the water was added to the driedpowder, mixed throughly and allowed to stand for two minutes to allowthe xanthan to hydrate. The mixture was placed on the hair strand andaggressively massaged into the hair strand for approximately 1 minute.The Rand was then placed in a 45° C. environment for 45 minutes. After45 minutes, the hair strand was rinsed with water and a mixture ofshampoo and water. After the hair strand was rinsed, thioglycolate wasapplied to the hair strand, and the hair strand was observed todetermine whether a reddish purple color was present to indicate thepresence of iron. The inventive composition and process was able toremove the iron after 45 minutes as evidenced lack of purple colorproduction.

The inventive process is utilized by washing the hair with shampoo andrinsing with warn water to open the hair cuticles, applying theinventive compositions and throughly working the gel into all hair andscalp utilizing massaging action and pressure of palms and fingertips.The inventive process also removes mineral deposits from the scalp.After the gel is massaged into the scalp and hair shafts, the gel isretained on the hair shafts and kept at an elevated temperature ofapproximately 45° C. The temperature may be maintained by use of a heatcap or hair dryer. The hair is also periodically massaged and the gelworked into the hair shafts to assure an even distribution of heat andthe composition throughout the hair to aid in mineral removal. Theinventive composition is recommended to be applied to the hair shaftsfor 10 minutes if a light mineral build-up is encountered, and up to 45minutes for a heavy mineral build-up. After the appropriate time haselapsed, the composition is rinsed off with water and a mixture of waterand detergent. It is also possible to repeat the the inventive processas it does not produce drying or harmful effects to the hair shafts.

Because minerals often become deeply embedded into the hair shafts, theinventive process requires the application of heat. The shafts arepreferably expanded by heat to open the cuticles and to make the hairmore porous to allow the inventive composition to reach thecysteine-mineral residues. The inventive process includes usingrelatively hot water to shampoo the hair, which expands the hair shafts,opens the cuticles and also increases the reaction rate. When the haircuticles are open, the inventive compositions are applied.

While the invention has been described in detail in the foregoingdescription, the same is to be considered as illustrative and notrestrictive in character, it being understood that only the preferredembodiment has been described, and that all changes and modificationsthat come within the spirit of the invention are desired to beprotected.

What is claimed is:
 1. An acidic aqueous composition suitable forremoving iron from hair comprising:(a) an acidifying agent effective toprovide an acidic environment of pH between about 2 and about 5 when thecomposition is used in solution on hair; (b) an ascorbic acid reducingagent present at a concentration of at least 2.1 percent w/w effectiveto reduce the oxidation state of iron ions bonded to hair from the Fe³⁺oxidation state to the Fe²⁺ oxidation state; (c) a chelating agenteffective to remove iron ions covalently bonded to hair, said chelatingagent comprising 1.5 percent disodium EDTA, 2.7 percent sodiumgluconate, 0.42 percent citric acid and 0.42 percent sodium citrate(w/w) of composition; (d) a gelling agent; and (e) water.
 2. Thecomposition of claim 1 wherein the ascorbic acid reducing agent ispresent at a concentration of 2.1 percent w/w of composition and thegelling agent is xanthan gum at a concentration of about 1 percent w/wof composition.
 3. A process for removing minerals from hair shaftscomprising the steps of:(a) providing a gel including:(i) an acidifyingagent effective to provide an acidic environment of pH between about 2and about 5 when the gel is used in solution on hair; (ii) an ascorbicacid reducing agent present at a concentration of at least about 2.1percent w/w effective to reduce the oxidation state of iron ions bondedto hair; (iii) a chelating agent effective to remove iron ionscovalently bonded to hair, said chelating agent comprising 1.5 percentdisodium EDTA, 2.7 percent sodium gluconate, 0.42 percent citric acid,and 0.42 percent sodium citrate w/w of said gel; (iv) a gelling agent;and (v) water; (b) contacting said gel with the hair shafts at anelevated temperature; (c) forcing and massaging said gel into said hairshafts; (d) leaving said gel on said hair shafts at a temperature ofabout 45° C. a sufficient time to remove iron from said hair shafts; and(e) rinsing said gel from said hair shafts with water.
 4. The process ofclaim 3 in which the chelating agent consists essentially of 30 percentdisodium EDTA, 55 percent sodium gluconate, 8 percent citric acid and 8percent sodium citrate (w/w).
 5. The process of claim 3 in which the gelcomprises 2.1 percent ascorbic acid and the gelling agent is xanthan gumat a concentration of 1 percent w/w of said gel.
 6. The process of claim5 in which the gel consists essentially of 2.1 percent ascorbic acid,1.5 percent disodium EDTA, 2.7 percent sodium gluconate, 0.42 percentcitric acid, 0.42 percent sodium citrate and 1 percent w/w xanthan gumw/w of the gel.